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1.
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Gibberellins A19, A20, and A1 were applied to seedlings of birch (Betula pubescens Ehrh.) and alder (Alnus glutinosa (L.) Gaertn.) in order to test their ability to counteract growth inhibition induced by growth retardants (ancymidol and BX-112) or short day (SD, 12 h) photoperiod. Ancymidol inhibits early and BX-112 inhibits late steps in gibberellin biosynthesis. BX-112 inhibited stem elongation in both species while ancymidol, applied as a soil drench, was effective in alder only. Growth retardants affected stem elongation mainly by inhibiting elongation of internodes. All three gibberellins were equally active when applied to seedlings treated with ancymidol; however, only GA1 was able to counteract the growth inhibition induced by BX-112. SD-induced cessation of elongation growth in birch was counteracted by GA1, and to some degree, by GA20, while GA19 was inactive. SD treatment did not induce cessation of apical growth in alder. These results are consistent with the hypothesis that of gibberellins belonging to the early C-13 hydroxylation pathway, GA1 is the only active gibberellin for stem elongation.  相似文献   

3.
The structures of four alkaloids extracted from Lycopodium lucidulum (Lycopodiaceae) were established by X-ray and 2D NMR spectroscopic analyses. The dihydro-derivative of oxolucidine A, which was obtained by NaBH4 reduction of oxolucidine A, was treated with p-bromobenzoyl chloride to afford crystals, whose X-ray crystallographic analysis established the stereostructure, including the absolute configuration. The 2D NMR spectra of tetrahydrodeoxylucidine B were fully analyzed to establish the full structure of lucidine B, and the hitherto unknown stereochemistry at the C-14 position was established as beta-H. The structure of a new alkaloid, lucidulinone, was determined by spectroscopic analysis to be luciduline lactam.  相似文献   

4.
Malonate, Malonyl-Coenzyme A, and Acetyl-Coenzyme A in Developing Rat Brain   总被引:2,自引:2,他引:0  
Abstract: Free malonate, malonyl-coenzyme A (malonyl-CoA), and acetyl-CoA were assayed in rat brain at developmental ages from the 20th day of gestation to 60 days of postnatal life. The determination of malonate was based on its conversion to malonyl-CoA and decarboxylation to acetyl-CoA by enzyme extracts from Pseudo-monas fluorescens. The resulting acetyl-CoA reacted with [4-14C]oxaloacetate to form [5-14C]citrate, which was isolated by TLC. Malonyl-CoA in perchloric acid extracts from brain was converted to acetyl-CoA by rat liver mitochondrial malonyl-CoA decarboxylase (EC 4.1.1.9). Acetyl-CoA derived from this step was assayed by a modified CoA-cycling procedure. Brain acetyl-CoA was also assayed by CoA cycling. Prenatal brain contained no free malonate but malonyl-CoA was present. The acetyl-CoA level was relatively high just prior to birth and declined slightly with growth. Malonate concentrations after birth rose rapidly to reach 192 nmol/g wet weight at 60 days. Adult levels for malonyl-CoA and acetyl-CoA were 1.83 and 1.90 nmol/g wet weight, respectively. The origin and natural role of free malonate in brain are not known but deacylation of malonyl-CoA by reversal of the malonyl-CoA synthetase reaction is postulated. Rat liver and kidney also contain substantial concentrations of free malonate.  相似文献   

5.
Riassunto Lo studio comprende una revisione critico-sperimentale della specie Actinomyces albus, della quale vengono considerati come sinonimi circa 30 nomi speeifici, fra i quale A. chromogenus, A. odorifer, A. thermophylus p.p.; della specie é data una diagnosi ed una particolareggiata descrizione.Sono inoltre studiate le specie A. viridis, (= A. viridochromogenus) e A. innominatus, n. nomen. Quest'ultima é preceduta da una breve discussione sulla specie A. homini.
Summary Twenty-six strains of Actinomyces albus are studied redescribed from morphological, cultural and biochemical standpoints. Many biological activities of A. chromogenus, A. odorifer and A. thermophilus are in common with other species of the same genus, so that they may be considered for sub-specific, (not specific) differentiation. A discussion on A. farcinicus, A. albidoflavus and A. aureus has been originated from mislabeling as A. albus; the group including the two last named species (flavus group) must be revised. A few strains classified A. farcinicus are in no doubt true A. albus, but this real specific entity remains to be revised from Nocard's strain. A. viridis, for the first time described by Lombardo-Pellegrino, has been redescribed three times as a new species under the same binomial, and the fourth as A. viridochromogenes. A. hominis Bostroem is an uncorrect determination for the species originally described by Waksmann and Curtiss, and it is renamed A. innominatus, the binomial A. (Streptothrix) hominis Auct. being a nomen ambiguum. In conclusion, 30 bionmial are appended in sinonimy to A. albus, including Cladothrix dichotoma Macé (1888) non Cohn, G. invulnerabilis Acosta et G. Rossi, C. odorifera Rullm. Actinomyces chromogenus Gasp., A. thermophilus Auct., p.p., A. (Streptothrix) Sanninii (Cif.) Westerd., A. Almquisti Duché, A. Gougeroti Duché, and so on.
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6.
Three two-phase chromatographic solvent systems, utilizing benzene (b), toluene (T) and alcohol/water mixtures (2-propanol = iP, 2-butanol = 2B, percent alcohol indicated), BiP45, TiP50 and T2B50 will separate ecdysterone, inokosterone, α-ecdysone, makisterone A and ponasterone A Cl). The reproducibility of the Rf's and resolution of these systems and two others tested were satisfactory with the difficult to separate ecdysterone-inokosterone pair. 3H-Ecdysterone label was recovered efficiently (86–94%) from paper chromatograms by ethanol elution.  相似文献   

7.
Abstract

Staphylococcal enterotoxins (SEs) are a family of structurally related exotoxin molecules produced by certain Gram-positive Staphylococcus aureus bacterial strains. SEs are a major cause of food poisoning and are involved in bacterial Gram-positive shock in humans. SEs bind to major histocompatibility complex (MHC) class II molecules on antigen-presenting cells (APCs) and subsequently activate a large fraction, 5–20%, of T lymphocytes (1). This property has led to their classification of superantigens (SAg). The T cells are activated by SAg to proliferate and produce cytokines such as interleukin-2 (IL-2), interferon-γ (IFN-γ), and tumor necrosis factor-α and β (TNF-α and β) (2,3). Depending on origin, superantigens can be divided in two groups, viral and bacterial. For reviews see Refs. 4–8.  相似文献   

8.
It has been shown that women receiving oral contraceptives have increased levels of serum vitamin A. High vitamin A levels may constitute a teratogenic hazard and it has been suggested that women who conceive soon after discontinuing oral contraceptive therapy may be especially at risk to this hazard.We have confirmed a significant increase in vitamin A levels in women taking oral contraceptives. During early pregnancy there is no significant difference in vitamin A levels between women who have recently been taking oral contraceptives and those who have not. We have been unable to show that either taking oral contraceptives shortly before pregnancy or a high vitamin A level during the first trimester of pregnancy, comparable to that of a woman taking oral contraceptives, has any detrimental effect on the outcome of pregnancy. It seems unlikely that women who conceive soon after discontinuing oral contraception run any teratogenic risk from increased vitamin A levels.  相似文献   

9.
10.
Four novel gibberellins GA30, GA31, GA33, GA34, five known gibberellins GA8, GA17 (free acid and its monomethyl ester), GA19, GA27, GA29 and the gibberellin-like substances were isolated from immature seeds of evening-glory (Calonyction aculeatum). The structures of GA30, GA31, GA33 and GA34 were elucidated as IX, XVIII, XXII and XXXIV, respectively. The three gibberellin-like substances were partially characterized.  相似文献   

11.
12.
MENHENETT  R. 《Annals of botany》1981,47(3):359-369
Interactions between the growth retardants daminozide (a substitutedsuccinamic acid) or piproctanyl bromide (a quaternary ammonium,piperidinium compound), and a subsequent application of a singledose (40 µg) of either gibberellin A1, A3, A4+7 or A12,showed that, in Chrysanthemum morifolium Ramat. cv. Bright GoldenAnne, a strong interdependence exists between elongation ofthe lateral shoot and the rate of development of its terminalinflorescence. A1, A3, and A4+7 were highly active in overcoming the restrictionson both internode extension and the rate of flower-bud developmentimposed by either retardant, suggesting that these two retardanteffects are caused by a deficiency of active gibberellins (GN).In the absence of retardant, A1, A3, and A4+7 markedly increasedstem elongation, and flowering occurred earlier than in plantsreceiving neither retardant nor GN. A13 the only 20-carbon GNtested, was much less active, while A5 had a relatively greatereffect on the time of flowering than on shoot elongation. Thus,it is not necessarily the rate of stem extension which determinesthe rate of inflorescence development. The response to different amounts of A1, A3 or A13 (1, 5, 10,20, or 50 µg per shoot) neither suggest that different‘threshold’ levels of a particular GN are requiredto induce increases in either stem elongation or in the rateat which inflorescences develop, nor did a change in the dosegiven lead to any consistent differential effect on these twoprocesses. Chrysanthemum morifolium Ramat., stem extension, inflorescence development, growth retardants, gibberellins  相似文献   

13.
A new, simple, and very sensitive assay for phospholipase A and C is described. The assay is based on the bioluminescence developed by the mutant of the bacterium Beneckea harveyi as a response to myristic acid released from dimyristoyl phosphatidylcholine by either phospholipase A or by a phospholipase C-lipase coupled system. It is possible to assay these enzymes at a rate corresponding to a release of as little as 1 to 2 pmol of myristic acid per minute.  相似文献   

14.
Human enterovirus species A (HEV-A) consists of at least 16 members of different serotypes that are known to be the causative agents of hand, foot, and mouth disease (HFMD), herpangina, and other diseases, such as respiratory disease and polio-like flaccid paralysis. Enterovirus 71 (EV71) and coxsackievirus A16 (CVA16) are the major causative agents of HFMD. CVA5, CVA6, CVA10, and CVA12 mainly cause herpangina or are occasionally involved with sporadic cases of HFMD. We have previously shown that human scavenger receptor class B, member 2 (SCARB2) is a cellular receptor for EV71 and CVA16. Using a large number of clinical isolates of HEV-A, we explored whether all clinical isolates of EV71 and other serotypes of HEV-A infected cells via SCARB2. We tested this possibility by infecting L-SCARB2 cells, which are L929 cells expressing human SCARB2, by infecting human RD cells that had been treated with small interfering RNAs for SCARB2 and by directly binding the viruses to a soluble SCARB2 protein. We showed that all 162 clinical isolates of EV71 propagated in L-SCARB2 cells, suggesting that SCARB2 is the critical receptor common to all EV71 strains. In addition, CVA7, CVA14, and CVA16, which are most closely related to each other, also utilized SCARB2 for infection. EV71, CVA14, and CVA16 are highly associated with HFMD, and EV71 and CVA7 are occasionally associated with neurological diseases, suggesting that SCARB2 plays important roles in the development of these diseases. In contrast, another group of viruses, such as CVA2, CVA3, CVA4, CVA5, CVA6, CVA8, CVA10, and CVA12, which are relatively distant from the EV71 group, is associated mainly with herpangina. None of these clinical isolates infected via the SCARB2-dependent pathway. HEV-A viruses can be divided into at least two groups depending on the use of SCARB2, and the receptor usage plays an important role in developing the specific diseases for each group.  相似文献   

15.
Although adenosine exerts cardio-and vasculoprotective effects, the roles and signaling mechanisms of different adenosine receptors in mediating skeletal muscle protection are not well understood. We used a mouse hindlimb ischemia-reperfusion model to delineate the function of three adenosine receptor subtypes. Adenosine A(3) receptor-selective agonist 2-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide (Cl-IBMECA; 0.07 mg/kg ip) reduced skeletal muscle injury with a significant decrease in both Evans blue dye staining (5.4 +/- 2.6%, n = 8 mice vs. vehicle-treated 28 +/- 6%, n = 7 mice, P < 0.05) and serum creatine kinase level (1,840 +/- 910 U/l, n = 13 vs. vehicle-treated 12,600 +/- 3,300 U/l, n = 14, P < 0.05), an effect that was selectively blocked by an A(3) receptor antagonist 3-ethyl-5-benzyl-2-methyl-6-phenyl-4-phenylethynyl-1,4-(+/-)-dihydropyridine-3,5-dicarboxylate (MRS-1191; 0.05 mg/kg). The adenosine A(1) receptor agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA; 0.05 mg/kg) also exerted a cytoprotective effect, which was selectively blocked by the A(1) antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 0.2 mg/kg). The adenosine A(2A) receptor agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS-21680; 0.07 mg/kg)-induced decrease in skeletal muscle injury was selectively blocked by the A(2A) antagonist 2-(2-furanyl)-7-[3-(4-methoxyphenyl)propyl]-7H-pyrazolo[4,3-e] [1,2,4]triazolo[1,5-C]pyrimidin-5-amine (SCH-442416; 0.017 mg/kg). The protection induced by the A(3) receptor was abrogated in phospholipase C-beta2/beta3 null mice, but the protection mediated by the A(1) or A(2A) receptor remained unaffected in these animals. The adenosine A(3) receptor is a novel cytoprotective receptor that signals selectively via phospholipase C-beta and represents a new target for ameliorating skeletal muscle injury.  相似文献   

16.
SYNOPSIS. Three polycyclic, polyether, monocarboxylic acid antibiotics produced by and extracted from a strain of Streptomyces albus and designated A204 sodium, A28695A, or A204np, were specifically tested for activity against hepatic and incidentally against intestinal coccidia of rabbits. All were effective in preventing infections and acceptable to young rabbits when prepared in pelleted feed. Weight gain, however, was not as good in inoculated, medicated rabbits as in noninoculated, nonmedicated controls.
No gross pathologic changes were detected except in the livers of inoculated, nonmedicated controls which were severely infected and greatly enlarged. Livers of medicated rabbits were uninfected and normal in appearance and size.  相似文献   

17.
Gibberellin A17, abscisic acid, and 4′-dihydrophaseic acid were identified by GC-MS of derivatized extracts from both immature and mature seeds of pear. Immature seeds also contained phaseic acid, gibberellins A25 and A45, and two presumed mono-hydroxylated derivatives of GA45, one of which was tentatively identified as 3β-hydroxy-GA45. Several presumed metabolites of abscisic acid were detected in both mature and immature seeds.  相似文献   

18.
To the extent that all biological phenomena are perceivable only through their physical manifestations, it may be justified to assume that all biological phenomena will be eventually represented in terms of physics; perhaps not of present day physics, but of some “extended” form of it. However, even if this should be correct, it must be kept in mind that representing individual biological phenomena in terms of physics is not the same as deducing from known physical laws the necessity of biological phenomena. Drawing an analogy from pure mathematics, it is possible that while every biological phenomenon may be represented in terms of physics, yet biological statements represent a class of “undecidable” statements within the framework of physics. Such a conjecture is reinforced by the history of physics itself and illustrated on several examples. The 19th century physicists tried in vain todeduce electromagnetic phenomena from mechanical ones. A similar situation may exist in regard to biological and social sciences. Quite generally, the possibility of representing a class B phenomena in terms of class A phenomena does not imply that the phenomena of class B can be deduced from those of class A. The consequences of the above on the relation between physics, biology, and sociology are studied. A tentative postulational formulation of basic biological principles are given and some consequences are discussed. It is pointed out that not only can the study of biological phenomena throw light on some physical phenomena, but that the study of social phenomena may be of value for the understanding of the structures and functions of living organisms. The possibility of a sort of “socionics” is indicated.  相似文献   

19.
20.
A Metaphor, a Field, and a Journal   总被引:1,自引:0,他引:1  
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